There is a need in the manufacturing of IC devices for inspection of electronic components such as leads and solder balls of semiconductor packages. Several systems are available for separate 2-D and 3-D inspection of semiconductor packages.
U.S. Pat. No. 5,956,134 discloses a lead inspection system that is operable to make both 2-D and 3-D measurements of semiconductor packages while there are relative movement between the lead inspection system and the semiconductor packages. This system includes a first optical sensor, e.g. a CCD camera, oriented to capture a 2-D image of a semiconductor device package and compare the image with a predetermined 2-D image stored in a central processing unit (CPU). A high intensity light source, such as a laser, generates a plane of light which is reflected off the leads of the semiconductor package to a second optical sensor, e.g. another CCD camera, wherein a 3-D image is generated. The CPU compares the 3-D image with the predetermined or calculated positional relationships of the leads to establish co-planarity of the lead tips, or lack thereof. This system also includes a sensor located such that the semiconductor package is centered in a field of view of the cameras to capture the respective images. The disadvantages of ‘134’ are that it has different centers in field of view for 2-D and 3-D respectively, and requires a separate mechanism to pick up and orientate the targeted device before inspection can be performed.
U.S. Pat. No. 6,118,540 discloses an inspection system for automatically inspecting 2-D and 3-D criteria of packaged semiconductor devices using a single camera and several laser sources. A 2-D lighting is provided to illuminate the object under inspection. A single camera captures the image of the object. This provides the image data for 2-D analysis by a computer coupled to the system. Multiple laser sources provide the illumination for performing 3-D criteria measurements. One disadvantage of this system is that one camera are used for both 2D and 3D inspection, which will slow down the inspection throughput. The disparity in the amount of data input from 2-D and 3-D criteria becomes a bottleneck for the inspection speed of the inspection system that uses only one camera.
U.S. Pat. No. 6,291,816 discloses an imaging system that utilizes both 2-D and 3-D scanning assemblies. The 2-D scanning assembly pre-scans a selected region of an object. The data from the 2-D scanning assembly is used to predetermine areas containing 3-D features of interest and to direct the 3-D scanning assembly. The 2-D scanning assembly includes a line camera or an area array camera. The 3-D scanning assembly includes a laser for 3-D illumination, an acoustic optical (AO) deflector and a position sensitive device (PSD) detector. This system is complicated and expensive to set up.
There remains a need for an inspection system that is relatively simple, compact and inexpensive to set up while improving the speed of 3D inspection.